Ice on roads has plagued drivers since vehicles first came into use. Many devices have been developed to help vehicles operate on icy roads. For example, studded tires can be placed on vehicles to improve traction. Not all states permit the use of studded tires, however, because these tires can do serious damage to dry roads. Perhaps the most prevalent method of improving traction on icy roads is applying salt or sand to the roads. Salt can raise the freezing point of water, thereby keeping the roads from icing up. However, salt is corrosive and can damage road surfaces, bridges and vehicles. Sand is popular because it provides needed traction with little or no ill effects. The gritty nature of sand provides a gripping surface for the vehicles. Most often, sand is placed on the roads by city or private crews, typically after a winter storm. Thus, for a time after the icing conditions, the roads may not be sanded. Moreover, even after the sand has been applied, it can be washed or blown away.
Sand is also used to help provide traction for railroad locomotives. These engines have metal wheels that ride on smooth metal rails. Such conditions produce poor traction at times. Railroads use sand to improve traction. The sand is sprayed through nozzles directly in front of the locomotive's wheels. This ensures that a minimum of sand need be applied to achieve the maximum traction.
The use of sand by railroads has been adopted for use in vehicles, although without much commercial success. Examples of such systems are found in the following U.S. Pat. No. 1,810,765 that teaches a sand bag that is placed in the fender before the tire, and an open nozzle that aims a stream of sand under the tire. Discharge of sand is controlled by means of a damper or similar device that is connected to a handle near the driver. U.S. Pat. No. 1,832,581 teaches use of a central sand hopper that feeds sand to the four wheels via conduits. Discharge is controlled from within the vehicle. Nozzles are used to dispense the sand in front of the wheels. U.S. Pat. No. 2,016,419 teaches a large sander for use with busses or other large vehicles. Here, the hopper system is operated by vacuum or pressure lines within the vehicle. U.S. Pat. No. 4,575,135 discloses a device for mounting a sand dispenser on the front of large trucks. This device has a large sand container that sits on top of a nozzle system. Here again, the unit is operated from within the vehicle and the sand is directed towards the tires. Finally, U.S. Pat. No. 5,118,142 teaches use of a central hopper that distributes sand to the wheels via a number of conduits. Again, the sand is directed toward the tires of the vehicle or immediately in front thereof.
As noted above, a key element of providing a sanding system is that the sand must be kept dry. In freezing weather, wet sand freezes as solidly as concrete, making it useless. Moreover, modern vehicles travel at too high a speed to try to place sand directly in front of the wheels, as it is applied in locomotives. Typically, the tires pass over the sand too quickly to do much good unless a steady stream of sand is applied during braking. Such a system requires a large amount of sand to be stored in the vehicle. Moreover such as system also requires frequent refilling with large quantities of sand, which takes time and money. Thus, all the devices discussed above is not be practical for today's vehicles.